Method for generating control information based on characteristic data included in metadata

ABSTRACT

An apparatus according to one aspect of the present disclosure includes: one or more memories, and circuitry which, in operation; decodes a video stream to generate a first video signal with a first luminance range; acquires characteristic data indicating the luminance range of the first video signal; converts the characteristic data into control information according to a predetermined transmission protocol; and outputs the control information in accordance with the predetermined transmission protocol.

BACKGROUND 1. Technical Field

The present disclosure relates to a data output apparatus, a data outputmethod, and a data generation method.

2. Description of the Related Art

Conventionally, an Image signal processing apparatus for improving adisplayable luminance level is disclosed (for example, refer toUnexamined Japanese Patent Publication No. 2008-167418).

SUMMARY

The above-described conventional technology needs further improvement.

In one general aspect, the techniques disclosed here feature anapparatus including: one or more memories, and circuitry which, inoperation; decodes a video stream to generate a first video signal witha first luminance range; acquires characteristic data indicating theluminance range of the first video signal; converts the characteristicdata into control information according to a predetermined transmissionprotocol; and outputs the control information in accordance with thetransmission protocol.

Note that these general or specific aspects may be implemented using asystem, a method, an integrated circuit, a computer program, or acomputer-readable recording medium such as a CD-ROM, or may beimplemented using any combination of a system, a method, an integratedcircuit, a computer program, and a computer-readable recording medium.

The above-described aspect can achieve further improvement.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram Illustrating evolution of video techniques;

FIG. 2 is a diagram illustrating a relationship among masters, deliveryschemes, and display apparatuses in introducing HDR;

FIG. 3 is an illustrative diagram of a determination method of a codevalue of a luminance signal to be stored in content, and a process ofrestoring a luminance value from the code value during playback;

FIG. 4 is a diagram Illustrating an example of HDR metadata;

FIG. 5 is a diagram Illustrating an example of storage of static HDRmetadata;

FIG. 6 is a diagram Illustrating an example of storage of dynamic HDRmetadata;

FIG. 7 is a flowchart of a transmission method of the static HDRmetadata;

FIG. 8 is a flowchart of a processing method of HDR metadata;

FIG. 9 is a block diagram illustrating a configuration of a data outputapparatus;

FIG. 10 is a diagram Illustrating an example of data structure of an SEImessage that stores the HDR metadata;

FIG. 11 is a diagram Illustrating an example of the data structure ofthe SEI message that stores the HDR metadata;

FIG. 12 is a diagram illustrating an example of a user guidance displaymethod;

FIG. 13 is a diagram illustrating an example of the user guidancedisplay method;

FIG. 14 is a diagram illustrating an example of the user guidancedisplay method;

FIG. 15 is a diagram illustrating an example of the user guidancedisplay method;

FIG. 16 is a diagram illustrating a playback operation of a dual disc;

FIG. 17 is a flowchart illustrating the playback operation of the dualdisc;

FIG. 18 is a diagram illustrating types of BD;

FIG. 19 is a diagram illustrating the type of BD in more detail;

FIG. 20 is a first diagram illustrating data volume to be recorded on aBD;

FIG. 21 is a second diagram illustrating the data volume to be recordedon the BD:

FIG. 22 is a diagram illustrating an example of combination of videostreams and graphic streams recorded on each disc of BD and dual-streamdisc;

FIG. 23 is a diagram Illustrating another example of combination ofvideo streams and graphic streams recorded on each disc of BD anddual-stream disc;

FIG. 24 is a diagram Illustrating still another example of combinationof video streams and graphic streams recorded on each disc of BD anddual-stream disc;

FIG. 25A is a diagram illustrating an example of display processing toconvert an HDR signal and to perform HDR display within an HDR TV;

FIG. 25B is a diagram illustrating an example of display processing toperform HDR display using an HDR-enabled playback apparatus and SDR TV;

FIG. 25C is a diagram illustrating an example of display processing toperform HDR display of the HDR-enabled playback apparatus and SDR TVconnected to each other via a standard interface;

FIG. 26 is a diagram illustrating conversion processing from HDR topseudo HDR;

FIG. 27A is a diagram illustrating an example of EOTF (Electro-OpticalTransfer Function) that supports each of HDR and SDR;

FIG. 27B is a diagram illustrating an example of inverse EOTF thatsupports each of HDR and SDR;

FIG. 28 is a block diagram illustrating a configuration of a conversionapparatus and display apparatus according to the exemplary embodiment;

FIG. 29 is a flowchart illustrating a conversion method and displaymethod to be performed by the conversion apparatus and display apparatusaccording to the exemplary embodiment;

FIG. 30A is a diagram illustrating first luminance conversion;

FIG. 30B is a diagram illustrating another example of the firstluminance conversion;

FIG. 31 is a diagram Illustrating second luminance conversion;

FIG. 32 is a diagram Illustrating third luminance conversion; and

FIG. 33 is a flowchart Illustrating detailed processing of displaysettings.

DETAILED DESCRIPTION

A data output apparatus according to one aspect of the presentdisclosure is an apparatus including: one or more memories, andcircuitry which, in operation; decodes a video stream to generate afirst video signal with a first luminance range; acquires characteristicdata indicating the luminance range of the first video signal; convertsthe characteristic data into control information according to apredetermined transmission protocol; and

outputs the control information in accordance with the transmissionprotocol.

This allows the data output apparatus to generate the controlInformation based on the characteristic data included in the metadata.

For example, the circuitry may further: acquire conversion auxiliarydata for converting the luminance range of the first video signal;convert the luminance range of the first video signal based on theconversion auxiliary data to generate a second video signal with asecond luminance range narrower than the first luminance range; andoutput at least one of the first video signal and the second videosignal in accordance with the transmission protocol.

This allows the data output apparatus to change the luminance range ofthe first video signal by using the conversion auxiliary data includedin the metadata.

For example, the circuitry may further acquire (i) first metadataregarding the luminance range of the first video signal and (ii) secondmetadata regarding the luminance range of the first video signal, thesecond metadata being acquired from the video stream, one of the firstmetadata and the second metadata may be used in common to a plurality ofimages included in a continuous playback unit of the video signal andincludes static metadata including the characteristic data, thecircuitry may convert the characteristic data included in the staticmetadata into the control information according to the transmissionprotocol, and when outputting the first video signal, the circuitry mayoutput the control information based on the static metadata.

For example, one of the first metadata and the second metadata mayfurther be used in common to a unit finer than the continuous playbackunit of the video signal, and may include dynamic metadata including thecharacteristic data, the circuitry may further convert thecharacteristic data included in the static metadata and thecharacteristic data included in the dynamic metadata into the controlinformation according to the transmission protocol, and when outputtingthe first video signal, the circuitry may output the control informationbased on the static metadata and the dynamic metadata.

For example, the circuitry may further acquire at least one of (i) firstmetadata regarding the luminance range of the first video signal and(ii) second metadata regarding the luminance range of the first videosignal, the second metadata being acquired from the video stream, andthe circuitry acquires the characteristic data and the conversionauxiliary data by analyzing at least one of the first metadata and thesecond metadata.

For example, the first metadata and the second metadata may be staticmetadata to be used in common to a plurality of images included in acontinuous playback unit of the first video signal, and when both thefirst metadata and the second metadata are acquired, the circuitry mayacquire the characteristic data and the conversion auxiliary data byanalyzing the first metadata.

For example, the first metadata and the second metadata may be staticmetadata to be used in common to a plurality of images included in acontinuous playback unit of the first video signal, when only the firstmetadata is acquired among the first metadata and the second metadata,the circuitry may acquires the characteristic data and the conversionauxiliary data by analyzing the first metadata, and when the secondmetadata is acquired, the circuitry may switch metadata to be used fromthe first metadata to the second metadata.

For example, when a display apparatus connected to the data outputapparatus supports video output with the luminance range of the firstvideo signal, the circuitry may output the first video signal and thecontrol information to the display apparatus.

For example, the circuitry may further determine whether the displayapparatus supports video output with the luminance range of the firstvideo signal in initialization processing of the transmission protocol.

For example, the circuitry may further (i) acquire first metadataregarding the luminance range of the first video signal and (ii) outputthe control information while synchronizing with the second video signalof which the first metadata becomes effective.

For example, the circuitry may further acquire first metadata regardingthe luminance range of the first video signal, the first metadata mayinclude type information indicating a type of the first metadata, thecircuitry may further use the type information to determine whether thedata output apparatus can interpret the first metadata, and when thedata output apparatus can interpret the first metadata, the circuitrymay acquire the characteristic data and the conversion auxiliary data byanalyzing the first metadata.

For example, the circuitry (i) may further acquire first metadataregarding the luminance range of the first video signal and (ii) thecircuitry may acquire the characteristic data and the conversionauxiliary data by analyzing the first metadata, the first metadata maybe stored in a Supplemental Enhancement Information (SEI) message ofHigh Efficiency Video Coding (HEVC), the SEI message may includeidentification information indicating whether the SEI message includesmetadata, and when the SEI message is acquired including theidentification information indicating that the SEI message includes themetadata and a display apparatus to which the data is output supportsinput of the control information, the circuitry may further output theSEI message as it is in accordance with the transmission protocol.

For example, when the display apparatus does not support the videooutput with the luminance range of the first video signal, the circuitrymay further (i) output the second video signal and the controlinformation to the display apparatus and (ii) cause the displayapparatus to display that the second video signal is displayed.

For example, when the display apparatus does not support the videooutput with the luminance range of the first video signal, the circuitrymay further cause the display apparatus to display a message for a userto select whether to display the second video signal.

For example, when the display apparatus does not support the videooutput with the luminance range of the first video signal, the circuitrymay further cause the display apparatus to display a message for a userto select one of a plurality of conversion schemes for conversion fromthe first luminance range into the second luminance range.

A data output method according to one aspect of the present disclosure amethod to be performed by a data output apparatus, the method including:decoding a video stream to generate a first video signal with a firstluminance range; acquiring characteristic data indicating the luminancerange of the first video signal; converting the characteristic data intocontrol information according to a predetermined transmission protocol;and outputting the control information in accordance with thetransmission protocol.

This allows the data output method to generate the control informationbased on the characteristic data included in the metadata.

A data generation method according to one aspect of the presentdisclosure is a method to be performed by a data generation apparatus,the method including: generating metadata regarding a luminance range ofa video signal, the metadata including characteristic data Indicatingthe luminance range of the video signal; and generating a video streamincluding the video signal and the metadata.

This allows the data generation method to generate the video streamincluding the metadata including the characteristic data. This allows,for example, the data output apparatus to generate the controlinformation based on the characteristic data included in the metadata.

For example, the metadata may include a basic section whoseinterpretation is necessary and an extended section whose interpretationis not necessary.

For example, the metadata may include a payload, information indicatingwhether data in the payload is the basic section or the extendedsection, and information indicating a data size of the payload.

For example, the metadata may be stored in a Supplemental EnhancementInformation (SEI) message of High Efficiency Video Coding (HEVC), andthe SEI message may include identification information Indicatingwhether the SEI message includes the metadata.

Note that these general or specific aspects may be implemented using asystem, a method, an integrated circuit, a computer program, or acomputer-readable recording medium such as a CD-ROM, or may beimplemented using any combination of a system, a method, an integratedcircuit, a computer program, and a computer-readable recording medium.

In addition, features described above will be described mainly in [8.Data output apparatus] through [14. User guidance display method 5]

The exemplary embodiment described below indicates one specific exampleof the present disclosure. Numerical values, shapes, materials, andcomponents indicated in the following exemplary embodiment. Dispositionsand connection forms of the components, steps, order of the steps, andthe like are one example, and do not intend to limit the presentdisclosure. Also, among the components described in the followingexemplary embodiment, components that are not described in anindependent claim which represents the highest concept are described asoptional components.

Exemplary Embodiment 1. Background

An HDR (High Dynamic Range) signal, which is an image signal with aluminance range higher than a luminance range of a conventional imagesignal, is delivered via a delivery medium, such as a package mediumincluding a Blu-ray (registered trademark, and so on) disc that storesthe HDR signal, broadcast, and OTT (Over The Top). Here, OTT meanscontent or service provided on the Internet, such as a website, video,and voice, or a company that provides such content or service. Thedelivered HDR signal is decoded by a device such as a Blu-ray device.The decoded HDR signal is sent to an HDR-enabled display apparatus (suchas a television, projector, tablet, and smart phone), and an HDR videois played by the HDR-enabled display apparatus.

An HDR technique is still in an early stage, and it is assumed that anew HDR scheme will be developed after the HDR technique introducedfirst is adopted. In this case, the new HDR scheme can be adopted bystoring the HDR signal (and metadata) of the newly created HDR scheme inthe HDR delivery medium. The present disclosure implements a method andapparatus that maintain compatibility by ensuring HDR playback of adelivery medium that stores a new HDR signal form (metadata) with anoriginal technique without changing a decoding apparatus designed for anoriginal delivery medium (for example, Blu-ray device). This method andapparatus enable an HDR decoding apparatus that supports the new scheme(for example. Blu-ray device) to support processing by the new HDRscheme.

First, transition of video techniques will be described with referenceto FIG. 1. FIG. 1 is a diagram illustrating evolution of the videotechniques.

Until now, high definition of video has focused on increase in a numberof display pixels. So-called 2K video is widely used, from 720×480-pixelStandard Definition (SD) video to 1920×1080-pixel High Definition (HD)video.

In recent years, introduction of so-called 4K video has started with aview toward higher definition of video, including 3840×1920-pixel UltraHigh Definition (UHD) video and 4096×1920-pixel 4K video.

In addition to high resolution of video through introduction of 4K,consideration is given to high definition of video through extension ofa dynamic range, enlargement of a color gamut, and addition orimprovement of a frame rate.

Among those improvements, regarding the dynamic range, HDR (High DynamicRange) attracts attention as a scheme that supports a luminance rangewith an extended maximum luminance value for representing bright lightincluding specular reflection light that cannot be represented bycurrent TV signals with brightness more similar to actual brightnesswhile maintaining dark area gradation in conventional video.Specifically, while a scheme of the luminance range supported byconventional TV signals is referred to as SDR (Standard Dynamic Range)with the maximum luminance value of 100 nit. HDR is assumed to extendthe maximum luminance value to 1,000 nit or more. Standardization of HDRis under way in organizations such as SMPTE (Society of Motion Picture &Television Engineers) and ITU-R (International Telecommunications UnionRadiocommunications Sector).

Assumed specific application of HDR includes broadcast, package media(such as Blu-ray disc), and Internet delivery, similarly to HD and UHD.

Hereinafter, in an HDR-enabled video, luminance of the video includes aluminance value within the luminance range of HDR. A luminance signalobtained through quantization of the luminance value of the video isreferred to as an HDR signal. In an SDR-enabled video, luminance of thevideo includes a luminance value within the luminance range of SDR. Aluminance signal obtained through quantization of the luminance value ofthe video is referred to as an SDR signal.

2. Relationship Among Masters, Delivery Schemes, and Display Apparatusesin Introducing HDR

FIG. 2 is a diagram illustrating a flowchart for producing SDR and HDRmasters for home entertainment, and a relationship among delivery mediaand display apparatuses.

A concept of HDR has been proposed and effectiveness of HDR in a conceptlevel has been confirmed. In addition, a first implementation method ofHDR has been proposed. However, HDR content has not been made in largequantities using this method, and the first implementation method hasnot been verified. Therefore, when full-fledged production of HDRcontent starts in the future, the current production scheme of HDR,particularly metadata may change.

3. How to Use EOTF

FIG. 3 is an illustrative diagram of a determination method of a codevalue of the luminance signal to be stored in content, and a process ofrestoring the luminance value from the code value during playback.

The luminance signal indicating luminance in this example is anHDR-enabled HDR signal. An image after grading is quantized by inverseEOTF of HDR, and the code value corresponding to the luminance value ofthe image is determined. Processing such as image coding is performedbased on this code value, and a video stream is generated. Duringplayback, a decoding result of the stream is converted into a linearsignal through inverse quantization based on EOTF of HDR, and theluminance value for each pixel is restored. Hereinafter, quantization ofHDR using inverse EOTF is referred to as “inverse EOTF conversion ofHDR”. Inverse quantization of HDR using EOTF is referred to as “EOTFconversion of HDR”. Similarly, quantization of SDR using inverse EOTF isreferred to as “inverse EOTF conversion of SDR”. Inverse quantization ofSDR using EOTF is referred to as “EOTF conversion of SDR”.

By using this luminance value and metadata, a video conversion processorperforms conversion into the luminance value that can be displayed by avideo display unit, so that the video display unit can display the HDRvideo. For example, when peak luminance of an original HDR video is2,000 nit and peak luminance of the video display unit is 800 nit, theluminance may be lowered through conversion.

Thus, the scheme of the HDR master is implemented through combination ofEOTF and metadata, and the HDR signal. Therefore, there is a possibilitythat time will come when more efficient EOTF and metadata are developedand an HDR scheme using such EOTF and metadata should be adopted.

Although it is unknown at this time what kind of scheme this new schemewill be, a possibility that EOTF will be changed and a possibility thatmetadata will be added are conceivable. In this case, the HDR signalitself will also change.

It is an object of the present disclosure to spread the use of HDR byreducing a risk that a user who has purchased an HDR-enabled deviceneeds to purchase a new device again, even when a transmission format ofHDR is changed as described above.

4. Metadata

FIG. 4 is a diagram illustrating an example of HDR metadata. The HDRmetadata includes conversion auxiliary information used for changing theluminance range of a video signal (DR conversion), and HDR controlinformation. Each piece of the information is one of, for example,static HDR metadata provided for each title, and, for example, dynamicHDR metadata provided for each frame. The static HDR metadata isclassified into one of necessary metadata (basic data) and optionalmetadata (extended data), and the dynamic HDR metadata is classifiedinto optional metadata. Note that details of each piece of theinformation will be described later.

5. HDR Metadata

Parameters indicating characteristics at a time of mastering in HDRcontent include the static HDR metadata that is fixed for each title oreach playlist, and the dynamic HDR metadata that is variable for eachscene. Here, the title and playlist are information indicating acontinuously played video signal. Hereinafter, the continuously playedvideo signal is referred to as a continuous playback unit.

For example, the static HDR metadata includes at least one of a type ofEOTF function (curve), 18% gray value, diffuse white value, knee point,and clip point. EOTF is information that associates a plurality ofluminance values with a plurality of code values, and is Information forchanging the luminance range of the video signal. Since the otherinformation is attribute information regarding luminance of the videosignal, the static HDR metadata may be called information regarding theluminance range of the video signal, and information for specifying theluminance range of the video signal.

Specifically, the 18% gray value and the diffuse white value indicatethe luminance value (nit) in a video with predetermined brightness thatserves as a reference, in other words, indicate reference brightness inthe video. More specifically, the 18% gray value indicates the luminancevalue (nit) after mastering of a body with a brightness of 18 nit beforemastering. The diffuse white value indicates the luminance value (nit)corresponding to white color.

Each of the knee point and clip point is a parameter of the EOTFfunction, and indicates a point at which the characteristic in EOTFchanges. Specifically, the knee point indicates a change point fromwhich an increment in the luminance value mapped on EOTF as luminance ofthe video signal (output luminance) over an increment in an originalluminance value at a time of photographing (input luminance) becomes avalue different from 1:1. For example, in FIG. 30A described later, theknee point is Information for specifying a point of deviation fromlinear change. The clip point Indicates a point at which clipping isstarted in the EOTF function. Here, clipping refers to converting aninput luminance value equal to or greater than a certain value into anidentical output luminance value. For example, in FIG. 30B describedlater, the clip point indicates a point from which the output luminancevalue will not change.

The type of EOTF function (curve) is, for example, EOTF of HDR and EOTFof SDR illustrated in FIG. 27A.

Thus, a content data generation method according to the presentexemplary embodiment is a content data generation method for generatingcontent data. The content data generation method includes: a firstgeneration step of generating a video signal, and the static HDRmetadata (first metadata) including Information used in common to aplurality of images included in a continuous playback unit of the videosignal (video signal that constitutes the continuous playback unit), theinformation regarding the luminance range of the video signal; and asecond generation step of generating the content data by associating thecontinuous playback unit with the static HDR metadata. For example, theinformation regarding the luminance range of the video signal isinformation for converting the luminance range of the video signal.

The static HDR metadata includes information for specifying EOTF thatassociates the plurality of luminance values with the plurality of codevalues. The luminance value in the video signal is coded as the codevalue.

The static HDR metadata further includes Information indicating theluminance value in the video signal with predetermined referencebrightness, or information indicating a point from which thecharacteristic in EOTF changes. For example, the static HDR metadataincludes information indicating the luminance value corresponding towhite color in the video signal (diffuse white value).

In the first generation step is further generated the dynamic HDRmetadata (second metadata), which is information used in common to unitsfiner than the continuous playback unit, and is information regardingthe luminance range of the video signal. For example, the informationregarding the luminance range of the video signal is information forconverting the luminance range of the video signal.

The dynamic HDR metadata is data such as a parameter indicating amastering characteristic different for each scene. Here, the masteringcharacteristic indicates a relationship between original luminance(before mastering) and luminance after mastering. For example, theparameter indicating the mastering characteristic is information similarto the above-described static HDR metadata, and in other words, is atleast one piece of information included in the static HDR metadata.

FIG. 5 is a diagram Illustrating an example of storage of the static HDRmetadata. This example is an example of storing the static HDR metadatain the playlist in a package medium such as a Blu-ray disc.

The static HDR metadata is stored as one of the metadata for each streamreferenced from the playlist. In this case, the static HDR metadata isfixed for each playlist. That is, the static HDR metadata is stored inassociation with each playlist.

In OTT the static HDR metadata may be stored in a manifest file that isreferenced before acquisition of the stream. That is, the content datageneration method according to the present exemplary embodiment mayInclude generating the video signal as a video stream, and storing thestatic HDR metadata in the manifest file that is referenced beforeacquisition of the video stream.

In broadcast, the static HDR metadata may be stored in a descriptorindicating an attribute of the stream. That is, the content datageneration method according to the present exemplary embodiment mayinclude generating the content data as the video stream, and storing thestatic HDR metadata Independently of the video stream as an identifierindicating the attribute of the video stream. For example, the staticHDR metadata may be stored as a descriptor in MPEG2-TS.

When the static HDR metadata is fixed for each title, the static HDRmetadata may be stored as management Information Indicating theattribute of the title.

FIG. 6 is a diagram illustrating an example of storage of the dynamicHDR metadata in the video stream. In MPEG-4 AVC or HEVC (High EfficiencyVideo Coding), data structure called SEI (Supplemental EnhancementInformation) is used to store information regarding playback control ofthe stream. Therefore, for example, the dynamic HDR metadata is storedin the SEI.

It is assumed that the dynamic HDR metadata is updated for each scene. Ahead of the scene is an access unit (AU) of a head of a random accessunit, such as GOP (Group Of Pictures). Therefore, the dynamic HDRmetadata may be stored in the head access unit in order of decoding inthe random access unit. The head access unit of the random access unitis an IDR picture or a non-IDR I picture to which SPS (SequenceParameter Set) is appended. Therefore, a receiving apparatus can acquirethe dynamic HDR metadata by detecting an NAL (Network Abstraction Layer)unit that constitutes the head access unit of the random access unit.Alternatively, a unique type may be imparted to the SEI that stores thedynamic HDR metadata.

Note that the type of EOTF function may be stored as attributeInformation or the like on the stream in SPS. That is, the content datageneration method according to the present exemplary embodiment mayinclude generating content data as a video stream coded by HEVC, andstoring information for specifying EOTF in SPS included in the videostream.

6. Transmission Method of the Static HDR Metadata

FIG. 7 is a diagram illustrating a transmission method of the static HDRmetadata, and is a flowchart illustrating an example of an operation inwhich a playback apparatus such as a BD player (Blu-ray device) and arecorder transmits the HDR signal to the display apparatus viatransmission protocols such as HDMI (registered trademark, and so on).

As described above, the static HDR metadata is fixed for each title orplaylist. Therefore, where the static HDR metadata needs to be set (Yesin S401), the playback apparatus acquires the static HDR metadata fromcontent management information when starting playback of the title orplaylist, and stores and transmits the acquired static HDR metadata asHDMI control Information. That is, before starting transmission of thevideo signal that constitutes the title or playlist, the playbackapparatus acquires the static HDR metadata that corresponds to the titleor playlist, and transmits the acquired static HDR metadata as the HDMIcontrol information (S402). More generally, when performinginitialization processing of HDMI between the playback apparatus and thedisplay apparatus, the playback apparatus may transmit the static HDRmetadata as initialization Information.

Subsequently, the playback apparatus transmits the video streamcorresponding to the static HDR metadata (S403). Note that, to thisvideo stream, the transmitted static HDR metadata is effective.

Thus, the video stream transmission method according to the presentexemplary embodiment is a video stream transmission method fortransmitting the video stream. The video stream transmission methodincludes: an acquisition step of acquiring content data including thevideo signal, and the static HDR metadata (first metadata) regarding theluminance range of the video signal, the static HDR metadata beinginformation used in common to a plurality of images included in thecontinuous playback unit; and a transmission step of transmitting thevideo stream corresponding to the video signal, and the static HDRmetadata.

For example, in the transmission step, the video stream and the staticHDR metadata are transmitted in accordance with a communication protocolof HDMI.

The dynamic HDR metadata is transmitted as part of the video stream.

Note that the playback apparatus may transmit the dynamic HDR metadataas the HDMI control signal with timing with which the dynamic HDRmetadata becomes effective. At this time, the playback apparatustransmits the static HDR metadata and the dynamic HDR metadata whileproviding identifiers or the like to the static HDR metadata and thedynamic HDR metadata to identify the pieces of metadata.

The control signal may prescribe only data structure of a container forstoring the dynamic HDR metadata to allow the content of the SEI to becopied as it is as payload data of the container. This allows theplayback apparatus such as a BD player, even if syntax of the dynamicHDR metadata included in the SEI is updated, to support the updatewithout change in implementation of the playback apparatus.

In a similar manner for the static HDR metadata, if the static HDRmetadata in the content management information can be copied andtransmitted, the playback apparatus may support change in syntax of thestatic HDR metadata without change in implementation of the playbackapparatus. That is, the data structure of the container for storing thestatic HDR metadata is prescribed, and in the transmission step, thestatic HDR metadata included in the content data may be copied to thepayload of the container, and the container may be transmitted.

7. Processing Method of the HDR Metadata

FIG. 8 is a flowchart Illustrating an example of a processing method ofthe HDR metadata when the display apparatus displays the HDR signal.First, the display apparatus acquires the static HDR metadata from theHDMI control Information (S411), and determines a display method of theHDR signal based on the acquired static HDR metadata (S412).

When the control information does not include the static HDR metadata,the display apparatus determines the display method of the HDR signalbased on a value prescribed in advance in an application standard, ordefault settings of the display apparatus. That is, when the static HDRmetadata cannot be acquired, the video display method according to thepresent exemplary embodiment determines the display method of a videocorresponding to the video signal based on the predetermined value orsettings.

When the dynamic HDR metadata is detected in the SEI or the like withinthe video stream (Yes in S413), the display apparatus updates thedisplay method of the HDR signal based on the dynamic HDR metadata(S414). That is, in the video display method according to the presentexemplary embodiment, when the static HDR metadata is acquired, thedisplay method is determined based on the acquired static HDR metadata,and the video is displayed. When the dynamic HDR metadata is acquired,the display method determined based on the static HDR metadata isupdated to a display method determined based on the dynamic HDRmetadata, and the video is displayed. Alternatively, the display methodmay be determined based on both the static HDR metadata and the dynamicHDR metadata.

Note that when the display apparatus does not support acquisition of thedynamic HDR metadata, the display apparatus may operate only based onthe static HDR metadata. Even when the display apparatus supportsacquisition of the dynamic HDR metadata, the display apparatus may beunable to update the display method of the HDR signal whilesynchronizing with display time (PTS: Presentation Time Stamp) of theaccess unit that stores the metadata. In this case, after acquiring themetadata, the display apparatus may update the display method from theaccess unit to be displayed after earliest time when the display methodcan be updated.

Note that the display apparatus may support the update and addition ofthe parameter by imparting version information, etc. to the HDRmetadata. This allows the display apparatus to determine whether themetadata can be interpreted based on the version information of the HDRmetadata. Alternatively, the HDR metadata may include a basic sectionand an extended section, and the update or addition of the parameter maybe Implemented by change in the extended section while the basic sectionis not updated. That is, each of the static HDR metadata and the dynamicHDR metadata may have a plurality versions, and may include the basicsection used in common to the plurality of versions and the extendedsection different for each version. This allows the display apparatus tosecure backward compatibility based on the HDR metadata of the basicsection.

Thus, the video display method according to the present exemplaryembodiment is a video display method for displaying the video based onthe video stream. The video display method includes: an acquisition stepof acquiring the video stream corresponding to the video signal, and thestatic HDR metadata (first metadata); and a display step of determininga display method of the video corresponding to the video signal based onthe static HDR metadata, and displaying the video.

The luminance value in the video signal is coded as the code value. Thestatic HDR metadata includes information for specifying EOTF thatassociates the plurality of luminance values with the plurality of codevalues. In the display step, the video is generated by conversion of thecode value indicated by the video signal into the luminance value byusing EOTF specified by the static HDR metadata.

8. Data Output Apparatus

FIG. 9 is a block diagram illustrating a configuration of data outputapparatus 400 that outputs the HDR signal, such as a BD player. The HDRmetadata that is input Into data output apparatus 400 includescharacteristic data indicating the mastering characteristic of the HDRsignal, and conversion auxiliary data indicating a tone mapping methodfor converting the HDR signal into the SDR signal or converting thedynamic range of the HDR signal. These two types of metadata are storedas the static HDR metadata or the dynamic HDR metadata, as described inFIG. 5 and FIG. 6. Furthermore, the static HDR metadata is stored in atleast one of the content management information and the video stream.

Data output apparatus 400 includes video decoder 401, external metadataacquisition unit 402, HDR metadata interpreter 403, HDR controlinformation generator 404, DR converter 405, and HDMI output unit 406.

Video decoder 401 decodes the video stream, which is a coded stream ofvideo, to generate the video signal (first video signal), and outputsthe obtained video signal to DR converter 405. In addition, videodecoder 401 acquires the HDR metadata within the video stream (secondmetadata) (static HDR metadata or dynamic HDR metadata). Specifically,video decoder 401 outputs the HDR metadata stored in an SEI message orthe like of MPEG-4 AVC or HEVC to HDR metadata interpreter 403.

External metadata acquisition unit 402 acquires the static HDR metadata(first metadata) stored in the content management information, such as aplaylist, and outputs the acquired static HDR metadata to HDR metadatainterpreter 403. Here, the dynamic HDR metadata that may be changed in apredetermined unit that allows random access, such as a play item, maybe stored in the content management information. In this case, externalmetadata acquisition unit 402 acquires the dynamic HDR metadata from thecontent management information, and outputs the acquired dynamic HDRmetadata to HDR metadata interpreter 403.

HDR metadata interpreter 403 determines a type of HDR metadata that isoutput from video decoder 401 or external metadata acquisition unit 402,outputs the characteristic data to HDR control information generator404, and outputs the conversion auxiliary data to DR converter 405.

When the static HDR metadata is acquired by both video decoder 401 andexternal metadata acquisition unit 402, only the static HDR metadatathat is output from external metadata acquisition unit 402 may be usedas effective metadata. That is, where the first metadata acquired byexternal metadata acquisition unit 402 and the second metadata acquiredby video decoder 401 are the static HDR metadata used in common to aplurality of images included in the continuous playback unit of thefirst video signal, when HDR metadata interpreter 403 acquires both thefirst metadata and the second metadata, HDR metadata interpreter 403analyzes the first metadata to acquire the characteristic data and theconversion auxiliary data.

Alternatively, when external metadata acquisition unit 402 acquires thestatic HDR metadata, HDR metadata interpreter 403 uses the static HDRmetadata as effective metadata. Furthermore, when video decoder 401acquires the static HDR metadata, HDR metadata interpreter 403 mayoverwrite the effective metadata with the static HDR metadata. That is,in a case where the first metadata acquired by external metadataacquisition unit 402 and the second metadata acquired by video decoder401 are the static HDR metadata used in common to the plurality ofimages included in the continuous playback unit of the first videosignal, when only the first metadata is acquired among the firstmetadata and the second metadata, HDR metadata interpreter 403 analyzesthe first metadata to acquire the characteristic data and the conversionauxiliary data. When the second metadata is acquired, HDR metadatainterpreter 403 switches metadata to be used from the first metadata tothe second metadata.

HDR control information generator 404 generates the HDR controlinformation in HDMI based on the characteristic data, and outputs thegenerated HDR control information to HDMI output unit 406. Here,regarding the dynamic HDR metadata, output timing of the HDR controlinformation in HDMI output unit 406 is determined so that the HDRcontrol information can be output synchronizing with the video signal ofwhich the metadata becomes effective. That is, HDMI output unit 406outputs the HDR control Information while synchronizing with the videosignal of which the metadata becomes effective.

Based on the conversion auxiliary data, DR converter 405 converts thedecoded video signal into the SDR signal, or converts the dynamic range.Here, if the display apparatus connected to data output apparatus 400supports input of the HDR signal, conversion by DR converter 405 isunnecessary. Therefore, data output apparatus 400 may determine whetherconversion processing is necessary by confirming whether the connecteddisplay apparatus supports input of the HDR signal in HDMIinitialization processing, etc. When it is determined that theconversion processing is unnecessary, the first video signal obtained byvideo decoder 401 is input into HDMI output unit 406, without passingthrough DR converter 405.

That is, when the display apparatus connected to data output apparatus400 supports the video output with the luminance range of the HDR signal(first video signal), HDMI output unit 406 outputs the first videosignal and the HDR control information to the display apparatus. On theother hand, when the display apparatus connected to data outputapparatus 400 falls to support the video output with the luminance rangeof the HDR signal (first video signal), HDMI output unit 406 outputs thesecond video signal obtained by converting HDR into SDR, and the HDRcontrol information to the display apparatus. HDMI output unit 406determines in initialization processing of the transmission protocol(for example, HDMI) whether the display apparatus supports the videooutput with the luminance range of the HDR signal (first video signal).

HDMI output unit 406 outputs the video signal that is output from DRconverter 405 or video decoder 401, and the HDR control information inaccordance with the HDMI protocol.

Similar configuration may also be used when data output apparatus 400receives and outputs broadcast or OTT content. When data outputapparatus 400 and the display apparatus are included in a single device,HDMI output unit 406 is unnecessary.

In the above description, data output apparatus 400 includes externalmetadata acquisition unit 402 that acquires the metadata from themanagement information or the like, and video decoder 401 has a functionof acquiring the metadata from the video stream. However, data outputapparatus 400 may have only either one.

The above description has mentioned an example in which data outputapparatus 400 outputs data (video signal and HDR control information)according to HDMI. However, data output apparatus 400 may output dataaccording to any transmission protocol.

Thus, data output apparatus 400 includes: the decoder (video decoder401) that decodes the video stream to generate the first video signalwith a first luminance range (HDR); the acquisition unit that acquiresthe first metadata regarding the luminance range of the first videosignal (at least one of video decoder 401 and external metadataacquisition unit 402); the interpreter that interprets the firstmetadata to acquire the characteristic data indicating the luminancerange of the first video signal (HDR metadata interpreter 403); thecontrol information generator that converts the characteristic data intothe HDR control information according to the predetermined transmissionprotocol (for example, HDMI) (HDR control information generator 404);and the output unit that outputs the HDR control information inaccordance with the predetermined transmission protocol (HDMI outputunit 406).

This allows data output apparatus 400 to generate the controlinformation based on the characteristic data included in the metadata.

The interpreter (HDR metadata interpreter 403) further interprets thefirst metadata to acquire the conversion auxiliary data for convertingthe luminance range of the first video signal. Data output apparatus 400further includes the converter (DR converter 405) that converts theluminance range of the first video signal based on the conversionauxiliary data to generate the second video signal with the luminancerange narrower than the luminance range of the first video signal. Theoutput unit (HDMI output unit 406) further outputs at least one of thefirst video signal and the second video signal in accordance with thepredetermined transmission protocol.

This allows data output apparatus 400 to change the luminance range ofthe first video signal by using the conversion auxiliary data includedin the metadata.

The decoder (video decoder 401) further acquires the second metadata(HDR metadata) regarding the luminance range of the first video signalfrom the video stream. The interpreter (HDR metadata interpreter 403)analyzes at least one of the first metadata and the second metadata toacquire the characteristic data and the conversion auxiliary data.

As illustrated in FIG. 4, the static HDR metadata includes the necessarymetadata and the optional metadata, and the dynamic HDR metadataincludes only the optional metadata. That is, the static HDR metadata isalways used, while the dynamic HDR metadata is used selectively. Thus,the first metadata acquired by external metadata acquisition unit 402 orthe second metadata acquired by video decoder 401 is used in common tothe plurality of images included in the continuous playback unit of thevideo signal, and includes the static HDR metadata (static metadata)including the characteristic data. HDR control Information generator 404converts the characteristic data Included in the static HDR metadataInto the HDR control Information according to the predeterminedtransmission protocol. When outputting the first video signal (HDRsignal), HDMI output unit 406 outputs the HDR control information basedon the static HDR metadata.

The first metadata acquired by external metadata acquisition unit 402 orthe second metadata acquired by video decoder 401 is used in common to aunit finer than the continuous playback unit of the video signal, andincludes the dynamic HDR metadata (dynamic metadata) including thecharacteristic data. HDR control information generator 404 converts thecharacteristic data included in the static HDR metadata and specificdata included in the dynamic HDR metadata into the HDR controlinformation according to the predetermined transmission protocol. Whenoutputting the first video signal (HDR signal), HDMI output unit 406outputs the HDR control information based on the static HDR metadata andthe dynamic HDR metadata.

The data generation method according to the present disclosure is a datageneration method to be performed by the data generation apparatus, andincludes a first generation step of generating the metadata regardingthe luminance range of the video signal, and a second generation step ofgenerating the video stream including the video signal and the metadata.The metadata Includes the characteristic data Indicating the luminancerange of the video signal, and the conversion auxiliary data forconverting the luminance range of the video signal.

9. Example of Storage of the HDR Metadata

FIG. 10 is a diagram illustrating an example of data structure of theSEI message that stores the HDR metadata. As illustrated in FIG. 10, theSEI message dedicated to the HDR metadata may be defined. That is, themetadata may be stored in the message dedicated to the metadata.

Alternatively, the HDR metadata may be stored in a general-purpose SEImessage for user data storage, and information indicating that the HDRmetadata is stored in the message (HDR extended identificationinformation described later) may be provided in a payload section of themessage.

The HDR metadata includes the static HDR metadata and the dynamic HDRmetadata. In addition, flag information indicating whether the staticHDR metadata is stored, and flag information indicating whether thedynamic HDR metadata is stored may be provided. This allows the use ofthree kinds of storage methods, including a method for storing only thestatic HDR metadata, a method for storing only the dynamic HDR metadata,and a method for storing both the static HDR metadata and the dynamicHDR metadata.

Furthermore, the basic data (basic section) whose interpretation isnecessary and the extended data (extended section) whose interpretationis optional (interpretation is not necessary) may be defined to eachpiece of the metadata. For example, type information indicating a type(basic data or extended data) and a size of metadata are included inheader information, and a format of the container that stores themetadata is defined in the payload. That is, the metadata includes thepayload, the information indicating whether the data in the payload isthe basic data or the extended data, and the information indicating thedata size of the payload. In other words, the metadata includes the typeinformation indicating the type of metadata. For example, the basic datais stored in the container whose type value is 0. In addition, theextended data is assigned with a value equal to or larger than 1 as thetype value, and the type of extended data is indicated by the value.

The data output apparatus and the display apparatus acquire data in thecontainer that the data output apparatus and the display apparatus caninterpret with reference to the type value. That is, the data outputapparatus (or display apparatus) uses the type information to determinewhether the data output apparatus (or display apparatus) is capable ofinterpreting the metadata. When the data output apparatus (or displayapparatus) is capable of interpreting the metadata, the data outputapparatus (or display apparatus) interprets the metadata to acquire thecharacteristic data and the conversion auxiliary data.

The metadata may be generated so that a maximum size of the HDR metadatabe set in advance, and that a sum total of the size of the basic dataand the size of the extended data be equal to or less than the maximumsize. That is, the maximum value of the data size of the metadata isprescribed, and in the data generation method according to the presentdisclosure, the metadata is generated so that the data size of the sumof the basic data and the extended data is equal to or less than themaximum value.

By including a memory for this maximum size, the data output apparatusand the display apparatus can guarantee that all HDR metadata be storedwithin the memory. Alternatively, it is also possible to secure a dataarea of a fixed size for the static HDR metadata or the dynamic HDRmetadata, and to leave areas other than an area that stores the basicdata as areas for future extension.

Such data structure may be used for storing the HDR metadata in thecontent management information.

FIG. 11 is a diagram Illustrating an example of data structure in a casewhere the HDR metadata is stored in the SEI message for user datastorage. The data structure of FIG. 11 is similar to the data structureof FIG. 10 except that the message includes the HDR extendedidentification information and an extended type ID. The HDR extendedidentification Information Indicates that the message Includes the HDRmetadata. The extended type ID indicates Information such as a versionof the HDR metadata. That is, the metadata is stored in the SEI messageof HEVC, and the SEI message Includes the HDR extended identificationInformation indicating whether the metadata is included in the SEImessage.

In this case, the data output apparatus receives the SEI message foruser data storage including the HDR extended identification information,and when the display apparatus connected to the data output apparatussupports input of the HDR signal and the HDR control information, thedata output apparatus copies and outputs the received SEI message as itis in accordance with a protocol of output I/F to the display apparatus,such as HDMI. That is, when the SEI message is acquired including theHDR extended identification information indicating that the SEI messageincludes the metadata, and the display apparatus to which the data isoutput supports input of the HDR control Information, the data outputapparatus outputs the SEI message as it is in accordance with thepredetermined transmission protocol (for example, HDMI).

This allows the data output apparatus to output the HDR metadata to thedisplay apparatus regardless of content of the metadata. Such aconfiguration allows the data output apparatus to output new HDRmetadata to the display apparatus, even when new DR conversionprocessing is developed and new HDR metadata is defined in the future,and a display apparatus that supports this new HDR metadata is connectedto the data output apparatus that does not support this new HDRmetadata. Such a configuration allows the display apparatus to implementDR conversion processing according to the new HDR metadata.

10. User Guidance Display Method 1

FIG. 12 is a diagram illustrating a user guidance display method in theBlu-ray device that performs the conversion processing from HDR to SDR.

Since an algorithm of the conversion processing from HDR to SDR has notbeen established, accurate conversion from HDR to SDR is difficult undercurrent circumstances. It is also possible to implement a plurality ofconversion processing algorithms from HDR to SDR.

Therefore, when a user inserts an HDR-enabled disc in an HDR-enabledBlu-ray device connected to an HDR-disabled TV, it is necessary toprovide appropriate user guidance.

When the HDR-enabled Blu-ray device connected to the HDR-disabled TVdetects start of the conversion processing from HDR to SDR, the Blu-raydevice displays a guidance message, for example, “This disc is anHDR-enabled disc. Since the TV you use is an HDR-disabled TV, instead ofan HDR video, an SDR video will be played which is obtained throughconversion processing from HDR to SDR performed by the Blu-ray device”.

Thus, when the display apparatus does not support video output with theluminance range of the first video signal (HDR signal), the data outputapparatus (Blu-ray device) outputs the second video signal (SDR signal)obtained through conversion from the first luminance range into thesecond luminance range, and the HDR control information to the displayapparatus, and causes the display apparatus to display that the secondvideo signal obtained through conversion from the first luminance rangeinto the second luminance range will be displayed.

11. User Guidance Display Method 2

FIG. 13 is a diagram illustrating the display method of the userguidance at a time of performing the conversion processing from HDRstored in a disc to SDR.

A message (menu) to be displayed by the Blu-ray device when theconversion processing from HDR to SDR is performed is stored in an HDRdisc, or a nonvolatile memory within the Blu-ray device, etc. Thisallows the Blu-ray device to display the message at a time of performingthe conversion processing from HDR to SDR. In this case, the message isdisplayed, for example, “This disc is an HDR-enabled disc. Since the TVyou use is an HDR-disabled TV, instead of an HDR video, an SDR videowill be played which is obtained through conversion processing from HDRto SDR performed by the Blu-ray device”.

12. User Guidance Display Method 3

FIG. 14 is a diagram illustrating the display method of the userguidance menu at a time of performing the conversion processing from HDRstored in a disc to SDR.

By using the Blu-ray menu, the Blu-ray device may display a message suchas, “This disc is an HDR-enabled disc. Since the TV you use is anHDR-disabled TV, instead of an HDR video, an SDR video will be playedwhich is obtained through conversion processing from HDR to SDRperformed by the Blu-ray device. Do you want to play it?”. When the userselects a “Play” button, the Blu-ray device starts displaying theconverted image. On the other hand, when the user selects “Do not play”,the Blu-ray device stops playing the converted image, and displays amessage prompting the user to insert an HDR-disabled Blu-ray disc.

Thus, when the display apparatus does not support the video output withthe luminance range of the first video signal (HDR signal), the dataoutput apparatus (Blu-ray device) causes the display apparatus todisplay the message for the user to select whether to display the secondvideo signal (SDR signal) obtained through conversion from the firstluminance range into the second luminance range.

13. User Guidance Display Method 4

FIG. 15 is a diagram illustrating the display method of the userguidance menu that allows selection of the processing method at a timeof performing the conversion processing from HDR stored within a disc toSDR.

When metadata for the conversion processing from HDR to SDR is stored inBlu-ray, the Blu-ray device displays that the metadata is stored inBlu-ray. The Blu-ray device displays a message prompting that morebeautiful conversion will be available if the user selects a specifiedconversion scheme. That is, with Java (registered trademark) commandswithin the disc, etc., determination is made what type of conversionprocessing from HDR to SDR is implemented in the Blu-ray device. Thisallows the Blu-ray device to display a selection menu of conversionprocessing schemes from HDR to SDR, such as, “This disc is anHDR-enabled disc. Since the TV you use is an HDR-disabled TV, instead ofan HDR video, an SDR video will be played which is obtained throughconversion processing from HDR to SDR performed by the Blu-ray device.Which method do you select? (Play by processing 1), (Play by processing3), (Do not play)”. Here, processing 1 and processing 3 are differenttypes of conversion processing from HDR to SDR.

Thus, when the display apparatus does not support video output of theluminance range of the first video signal (HDR signal), the data outputapparatus (Blu-ray device) causes the display apparatus to display themessage for the user to select one of the plurality of conversionschemes for converting the first luminance range into the secondluminance range.

14. User Guidance Display Method 5

Note that a similar message can also be displayed for broadcast. Forexample, a TV or playback apparatus that does not support the HDR signaldisplays a message by using an application of data broadcasting, etc,saying that a broadcast program uses the HDR signal and may not bedisplayed correctly when viewed with such a TV or playback apparatus. ATV or playback apparatus that supports the HDR signal may not displaythe message. In addition, a tag value indicating an attribute of themessage indicates that the message is an alarm message about the HDRsignal. The TV or playback apparatus that supports the HDR signaldetermines that display of the message is unnecessary with reference tothe tag value.

15. Playback Operation of Dual Disc 1

A playback operation of the HDR disc that stores only the HDR signal hasbeen described above.

Next, multiplex data to be stored in a dual disc that stores both theHDR signal and the SDR signal will be described with reference to FIG.16. FIG. 16 is a diagram illustrating the multiplex data to be stored inthe dual disc.

In the dual disc, as illustrated in FIG. 16, the HDR signal and the SDRsignal are stored as multiplex streams different from each other. Forexample, in an optical disc such as Blu-ray, data of a plurality ofmedia, such as video, audio, subtitles, and graphics, is stored as onemultiplex stream by an MPEG-2 TS-based multiplexing scheme called M2TS.These multiplex streams are referenced from metadata for playbackcontrol, such as the playlist. During playback, a player selects themultiplex stream to be played, or data of individual language stored inthe multiplex stream by analyzing the metadata. This example indicates acase where the playlist for HDR and the playlist for SDR are storedindividually, and where each playlist references the HDR signal or theSDR signal. Identification information or the like indicating that boththe HDR signal and the SDR signal are stored may be Indicatedseparately.

Although it is possible to multiplex both the HDR signal and the SDRsignal in an identical multiplex stream, it is necessary for suchmultiplexing to satisfy a buffer model, such as T-STD (System TargetDecoder) prescribed in MPEG-2 TS. In particular, it is difficult tomultiplex two videos with high bit rate within a range of apredetermined data reading rate. Therefore, preferably the multiplexstreams are separated.

It is necessary to store data of audio, subtitles, graphics, etc. ineach multiplex stream, and data volume increases as compared withmultiplexing in one stream. However, against the increase in the datavolume, the data volume of video can be reduced by using a video codingscheme with a high compression ratio. For example, changing MPEG-4 AVCused in conventional Blu-ray into HEVC (High Efficiency Video Coding) isexpected to provide improvement in the compression ratio by a factor of1.6 to 2. Only a combination that fits into capacity of an optical discmay be allowed to be stored in a dual disc, such as storing acombination of two 2K streams or a combination of a 4K stream and a 2Kstream, including a combination of a 2K HDR stream and a 2K SDR stream,and a combination of a 4K SDR stream and a 2K HDR stream, by prohibitingstorage of two 4K streams.

16. Playback Operation of Dual Disc 2

FIG. 17 is a flowchart illustrating the playback operation of the dualdisc.

First, the playback apparatus determines whether an optical disc to beplayed is a dual disc (S301). When it is determined that the opticaldisc to be played is a dual disc (Yes in S301), the playback apparatusdetermines whether an output destination TV is an HDR TV or SDR TV(S302). When it is determined that the TV is an HDR TV (Yes in S302),the processing advances to step 6303. When it is determined that the TVis an SDR TV (No in S302), the processing advances to step S304. In stepS303, the playback apparatus acquires a video signal of HDR from themultiplex stream including the HDR signal within the dual disc, anddecodes and outputs the video signal to the HDR TV. In step S304, theplayback apparatus acquires a video signal of SDR from the multiplexstream including the SDR signal within the dual disc, and decodes andoutputs the video signal to the SDR TV. When it is determined in stepS301 that the optical disc to be played is not a dual disc (No in S301),the playback apparatus determines whether playback is possible by apredetermined method, and decides a playback method based on a result ofthe determination (S305).

17. Types of Disc

As described above, in response to high resolution and high luminancerange of the display apparatus, a plurality of types of Blu-ray discadapted to specifications of the display apparatus (hereinafter referredto as BD) is provided. FIG. 18 is a diagram illustrating the types ofBD. As illustrated in FIG. 18, the following describes that a BD onwhich a video signal is recorded with the resolution of the firstresolution and the luminance range of the first luminance range isdescribed as a 2K_SDR-enabled BD. The video signal with the resolutionof the first resolution and the luminance range of the first luminancerange is stored on the BD as a stream. This stream is described as a2K_SDR stream. The 2K_SDR-enabled BD is a conventional BD.

Also, a BD on which a video signal is recorded with the resolution ofthe second resolution and the luminance range of the first luminancerange is described as a 4K_SDR-enabled BD. The video signal with theresolution of the second resolution and the luminance range of the firstluminance range is stored on the BD as a stream. This stream isdescribed as a 4K_SDR stream.

Similarly, a BD on which a video signal is recorded with the resolutionof the first resolution and the luminance range of the second luminancerange is described as a 2K_HDR-enabled BD. The video signal with theresolution of the first resolution and the luminance range of the secondluminance range is stored on the BD as a stream. This stream isdescribed as a 2K_HDR stream.

Also, a BD on which a video signal is stored with the resolution of thesecond resolution and the luminance range of the second luminance rangeis described as a 4K_HDR-enabled BD. The video signal with theresolution of the second resolution and the luminance range of thesecond luminance range is stored on the BD as a stream. This stream isdescribed as a 4K_HDR stream.

Note that the first resolution, which is for example so-called 2Kresolution (1920×1080, 2048×1080), may be any resolution including suchresolution. Hereinafter, the first resolution may be just described as2K.

Also, the second resolution, which is so-called 4K resolution(3840×2160, 4096×2160), may be any resolution including such resolution.The second resolution is resolution with a larger pixel number than thatof the first resolution.

Note that the first luminance range is, for example, SDR (the luminancerange with a peak luminance of 100 nit) described above. The secondluminance range is, for example, HDR (the luminance range with the peakluminance exceeding 100 nit) described above. The second luminance rangeincludes the entire first luminance range, and the peak luminance of thesecond luminance range is larger than the peak luminance of the firstluminance range.

FIG. 19 is a diagram illustrating the types of BD in more detail.

As Illustrated in FIG. 19 (c). (f), (g), and (h), a dual-stream disc maybe considered in which one BD supports a plurality of videorepresentation methods. The dual-stream disc is a BD on which aplurality of video signals for playing identical content is recorded. Atleast one of resolution and luminance range of the plurality of videosignals differs.

Specifically, the dual-stream disc Illustrated in FIG. 19 (c) is a BD onwhich the 4K_SDR stream and the 2K_SDR stream are recorded. Thedual-stream disc Illustrated in FIG. 19 (f) is a BD on which the 2K_HDRstream and the 2K_SDR stream are recorded.

The dual-stream disc illustrated in FIG. 19 (g) is a BD on which the4K_HDR stream and the 4K_SDR stream are recorded. The dual-stream discillustrated in FIG. 19 (h) is a BD on which the 4K_HDR stream and the2K_SDR stream are recorded.

Note that the dual-stream disc illustrated in FIG. 19 (c) is notnecessary because the Blu-ray device is capable of performing downconversion of resolution (hereinafter also referred to as down convert)from 4K to 2K.

18. Disc Capacity 1

Here, each BD as described above will be supplemented with reference toFIG. 20 and FIG. 21. FIG. 20 and FIG. 21 are diagrams each illustratingdata volumes to be recorded on a BD.

FIG. 20 and FIG. 21 each Illustrate the data volumes of streams actuallyused in each BD and dual-stream disc.

FIG. 20 illustrates a case where the streams with a resolution of 2K(2K_SDR streams and 2K_HDR streams) are compressed using MPEG-4 AVC. Bitrates of Movie length, lossless Audio, and Compressed Audio are asfollows. Note that the BD records voice streams for a number oflanguages (Lossless Audio and Compressed Audio).

Movie length: 150 min (14 to 18 mbps)

Lossless Audio: 0 to 2 languages (4.5 mbps)

Compressed Audio: 3 to 5 languages (1.5 mbps)

In this case, a maximum value (A), intermediate value (B), and minimumvalue (C) of necessary disc capacity are as follows.

(A) (18+4.5*2+1.5*5) mbps*(150*60) s/8=38.8 GB

(B) (16+4.5*1+1.5*3) mbps*(150*60) s/8=28.1 GB

(C) (14+4.5*0+1.5*3) mbps*(150*60) s/8=20.8 GB

In addition, FIG. 20 illustrates a case where streams with a resolutionof 4K (4K_SDR streams and 4K_HDR streams) are compressed using HEVC. Thebit rates of Movie length, lossless Audio, and Compressed Audio are asfollows.

Movie length: 150 min (35 to 40 mbps)

Lossless Audio: 0 to 2 languages (4.5 mbps)

Compressed Audio: 3 to 6 languages (1.5 mbps)

In this case, the maximum value (a), intermediate value (b), and minimumvalue (c) of necessary disc capacity are as follows.

(a) (40+4.5*2+1.5*5) mbps' (150*60) s/8=63.6 GB

40 (b) (37+4.5*0+1.5*4) mbps*(150*60) s/8=48.4 GB

(c) (35+4.5*0+1.5 3) mbps*(150*60) s/8=44.4 GB

Here, the disc capacity required for a dual-stream disc in which boththe 2K_HDR stream compressed using MPEG-4 AVC and the 2K_SDR streamcompressed using MPEG-4 AVC are recorded is calculated by (A)+(A),(B)+(B), and (C)+(C) described above. Specifically, the maximum value is77.6 GB, the intermediate value is 56.2 GB, and the minimum value is41.6 GB.

Since discs of 66 GB and 100 GB are used in addition to a conventionaldisc of 50 GB, the dual-stream discs described above are also feasiblefrom a viewpoint of capacity.

Here, the disc capacity required for the dual-stream disc in which boththe 4K_HDR stream compressed using HEVC and the 2K_HDR stream compressedusing HEVC are recorded is calculated as 96.8 GB according to (b)+(b)described above, and as 88.8 GB according to (c)+(c) described above.Therefore, such a dual-stream disc is feasible with a disc with acapacity of 100 GB.

Similarly, the disc capacity required for the dual-stream disc in whichboth the 4K_HDR stream compressed using HEVC and the 2K_SDR streamcompressed using MPEG-4 AVC are recorded is calculated as 91.7 GBaccording to (a)+(B) described above, and as 65.2 GB according to(c)+(C) described above. Therefore, such a dual-stream disc is feasiblewith a disc with a capacity of 100 GB or a disc with a capacity of 66GB.

19. Disc Capacity 2

Furthermore, another example will be described with reference to FIG.21. FIG. 21 illustrates a case where streams with a resolution of 2K(2K_SDR streams and 2K_HDR streams) are compressed using HEVC. The bitrates of Movie length, lossless Audio, and Compressed Audio are asfollows.

Movie length: 150 min (7 to 9 mbps)

Lossless Audio: 0 to 2 languages (4.5 mbps)

Compressed Audio: 3 to 5 languages (1.5 mbps)

In this case, the maximum value (A), intermediate value (B), and minimumvalue (C) of necessary disc capacity are as follows.

(α) (9+4.5*2+1.5*5) mbps*(150*60) s/8=25.3 GB

(β) (8+4.5*1+1.5*3) mbps*(150*60) s/8=19.1 GB

(γ) (7+4.50+1.5 3) mbps*(150*60) s/8=12.9 GB

Here, the disc capacity required for a dual-stream disc in which boththe 2K_HDR stream compressed using HEVC and the 2K_SDR stream compressedusing HEVC are recorded is calculated by (α)+(α), (β)+(β), and (γ)+(γ)described above. Specifically, the maximum value is 50.6 GB, the typicalvalue is 38.2 GB, and the minimum value is 25.8 GB.

Since discs of 66 GB and 100 GB are used in addition to a conventionaldisc of 50 GB, the dual-stream discs described above are also feasiblefrom a viewpoint of capacity.

Similarly, the disc capacity required for a dual-stream disc in whichboth the 4K_HDR stream compressed using HEVC and the 2K_SDR streamcompressed using HEVC are recorded is calculated as 88.9 GB according to(a)+(α) described above, as 67.5 GB according to (b)+(β) describedabove, as 61.3 GB according to (b)+(γ) described above, and as 57.3 GBaccording to (c)+(γ) described above. Therefore, such a dual-stream discis feasible with a disc with a capacity of 100 GB or a disc with acapacity of 66 GB.

20. Details of Disc Type 1

In more detail, a video stream and a graphic stream (stream of graphicsof a first exemplary embodiment) are recorded on the BD. Here, FIG. 22is a diagram illustrating an example of a combination of the videostreams and the graphic streams recorded on each disc for each BDincluding the dual-stream discs.

In FIG. 22, the graphic stream is recorded in a resolution of 2Kregardless of the resolution of the corresponding video stream, inconsideration of time and effort of content (BD) production. The graphicstream can be shared between the 2K_SDR stream and the 4K_SDR stream.However, the graphic stream is recorded in the luminance range adaptedto the luminance range of the corresponding video stream. When the videostream is HDR, the graphic stream of HDR is recorded. When the videostream is SDR, the graphic stream of SDR is recorded. Conversion of thegraphic stream from SDR to HDR is performed when content is produced.

21. Details of Disc Type 2

FIG. 23 is a diagram illustrating another example of the combination ofthe video streams and the graphic streams recorded on each disc for eachBD including the dual-stream discs.

In FIG. 23, the graphic stream is recorded in a resolution of 2K andluminance range of SDR regardless of the resolution and luminance rangeof the corresponding video stream, in consideration of time and effortof content production. The graphic stream can be shared among all of the2K_SDR stream, 4K_SDR stream, 2K_HDR stream, and 4K_HDR stream. In thiscase, both of conversion of the resolution of the graphic stream from 2Kto 4K, and conversion of the luminance range of the graphic stream fromSDR to HDR are performed by the Blu-ray device.

22. Details of Disc Type 3

FIG. 24 is a diagram illustrating still another example of thecombination of the video streams and the graphic streams recorded oneach disc for each BD including the dual-stream discs.

In FIG. 24, in order to eliminate the need for conversion of the graphicstream in the Blu-ray device, the graphic stream is recorded with theresolution and luminance range of the graphic stream adapted to theresolution and luminance range of the corresponding video stream whencontent is produced.

23. Summary

The Blu-ray device that plays a 4K-enabled BD or HDR-enabled BD needs tosupport four TVs, Including a 2K_SDR-enabled TV, 2K_HDR-enabled TV,4K_SDR-enabled TV, and 4K_HDR-enabled TV. Specifically, the Blu-raydevice needs to support three sets of HDMI/HDCP standards (HDMI 1.4/HDCP1.4, HDMI 2.0/HDCP 2.1, HDMI 2.1/HDCP 22).

Furthermore, when playing four types of Blu-ray discs (2K_SDR-enabledBD, 2K_HDR-enabled BD, 4K_SDR-enabled BD, and 4K_HDR-enabled BD), theBlu-ray device needs to select appropriate processing and HDMI/HDCP foreach BD (content) and for each connected display apparatus (TV).Furthermore, when compositing video and graphics, the Blu-ray deviceneeds to change the processing in accordance with the type of BD and thetype of connected display apparatus (TV).

This complicates internal processing of the Blu-ray devicesignificantly. The aforementioned third exemplary embodiment hasprovided various techniques for relatively simplifying the internalprocessing of the Blu-ray device.

[1] When the HDR signal is displayed on an HDR-disabled TV, theconversion from HDR to SDR is required. In order to make this conversionan option in the Blu-ray device, the aforementioned third exemplaryembodiment has proposed the BD configuration called dual-stream disc.

[2] In addition, the aforementioned third exemplary embodiment hasapplied limitation to the graphic stream to reduce the type ofcombination of the video stream and the graphic stream.

[3] The aforementioned third exemplary embodiment has significantlyreduced a number of combination of complicated processing steps in theBlu-ray device by the dual stream disc and limitation of the graphicstream.

[4] The aforementioned third exemplary embodiment has presented internalprocessing and HDMI processing that do not produce inconsistency inprocessing of the dual-stream disc, even when pseudo HDR conversion isintroduced.

In a case of displaying the HDR video on the SDR TV in the conversionmethod of the present disclosure, by making use of the fact that thepeak luminance of the SDR TV for display exceeds 100 nit (normally 200nit or more). “HDR to pseudo HDR conversion processing” is implementedthat allows conversion of the HDR video into a pseudo HDR video similarto an original HDR and display on the SDR TV, by converting the HDRvideo while maintaining gradation of a region exceeding 100 nit to someextent, instead of conversion of the HDR video into the SDR video of 100nit or less.

In this conversion method, the conversion method of the “HDR to pseudoHDR conversion processing” may be switched in accordance with thedisplay characteristic of the SDR TV (maximum luminance, input-outputcharacteristic, and display mode).

Conceivable acquisition methods of display characteristic informationinclude (1) automatic acquisition through HDMI or a network, (2)generation by causing the user to input Information such as amanufacturer name and model number, and (3) acquisition from a cloud,etc. using the information such as the manufacturer name and the modelnumber.

Conceivable acquisition timing of the display characteristic informationby conversion apparatus 100 includes (1) acquisition immediately beforepseudo HDR conversion, and (2) when connected to display apparatus 200(such as the SDR TV) for the first time (when the connection isestablished).

In this conversion method, the conversion method may be switched inaccordance with luminance information on the HDR video (CAL, CPL).

Examples of the conceivable acquisition method of the luminanceinformation on the HDR video by conversion apparatus 100 include (1)acquisition as metadata information appended to the HDR video, (2)acquisition by causing the user to input title information on content,and (3) acquisition from a cloud, etc. using input information that isinput by the user.

Details of the conversion method include (1) conversion so that theluminance would not exceed DPL, (2) conversion so that CPL would becomeDPL, (3) not changing the luminance equal to or less than CAL andvicinity thereof, (4) conversion using a natural logarithm, and (5) clipprocessing at DPL.

In order to enhance an effect of pseudo HDR, this conversion method mayinclude transmitting display settings such as a display mode and displayparameter of the SDR TV to display apparatus 200 for switching. Forexample, a message prompting the user to make display settings may bedisplayed on a screen.

24. Necessity for Pseudo HDR 1

Next, necessity for pseudo HDR will be described with reference to FIG.25A to FIG. 25C.

FIG. 25A is a diagram Illustrating an example of display processing forconverting an HDR signal and performing HDR display within an HDR TV.

As illustrated in FIG. 25A, in displaying an HDR video, a maximum valueof the luminance range of HDR (peak luminance (HPL (HDR Peak Luminance):example 1500 nit)) may not be displayed as it is even if the displayapparatus is an HDR TV. In this case, luminance conversion is performedto adapt a linear signal after inverse quantization using EOTF of HDR toa maximum value of the luminance range of the display apparatus (peakluminance (DPL (Display Peak luminance): example 750 nit)). Then,inputting a video signal obtained through the luminance conversion intothe display apparatus allows for displaying the HDR video adapted to themaximum luminance range which is a limit of the display apparatus.

FIG. 25B is a diagram illustrating an example of display processing forperforming HDR display by using an HDR-enabled playback apparatus andSDR TV.

As Illustrated in FIG. 25B, in displaying the HDR video, when thedisplay apparatus is an SDR TV, by making use of the fact that themaximum value of the luminance range of the SDR TV for display (peakluminance (DPL: example 300 nit)) exceeds 100 nit, “EOTF conversion ofHDR” performed in the HDR TV and “luminance conversion” using DPL(example: 300 nit), which is the maximum value of the luminance range ofthe SDR TV, are performed in the “HDR to pseudo HDR conversionprocessing” within the HDR-enabled playback apparatus (Blu-ray device)of FIG. 25B. If a signal obtained by performing the “luminanceconversion” can be input directly Into the “display apparatus” of theSDR TV, an effect identical to the effect of the HDR TV can be achievedeven if the SDR TV is used.

However, this cannot be achieved because the SDR TV does not have meansfor performing direct input of such a signal from outside.

FIG. 25C is a diagram illustrating an example of display processing forperforming HDR display using the HDR-enabled playback apparatus and SDRTV connected to each other via a standard interface.

As illustrated in FIG. 25C, it is necessary to input into the SDR TV asignal that provides the effect of FIG. 25B by using an input interfaceusually included in the SDR TV (such as HDMI). In the SDR TV, the signalthat is input via the input interface passes through “EOTF conversion ofSDR”, “luminance conversion for each mode”, and “display apparatus”sequentially, and displays a video adapted to the maximum luminancerange value of the display apparatus. Therefore, within the HDR-enabledBlu-ray device, a signal (pseudo HDR signal) is generated for cancelling“EOTF conversion of SDR” and “luminance conversion for each mode”through which the signal passes immediately after the input interface inthe SDR TV. That is, within the HDR-enabled Blu-ray device, byperforming “inverse luminance conversion for each mode”, and “inverseEOTF conversion of SDR” Immediately after “EOTF conversion of HDR” and“luminance conversion” using the peak luminance (DPL) of the SDR TV, apseudo effect Identical to the effect in a case where a signalImmediately after the “luminance conversion” is input into the “displayapparatus” (dashed arrow of FIG. 25C) is achieved.

25. Necessity for Pseudo HDR 2

A normal SDR TV, whose input signal is 100 nit, has capability of visualrepresentation of 200 nit or more adapted to viewing environments (darkroom: cinema mode, bright room: dynamic mode, etc.). However, since aluminance upper limit of the input signal to the SDR TV is determined as100 nit, the capability cannot be used directly.

In a case of displaying the HDR video on the SDR TV, by making use ofthe fact that the peak luminance of the SDR TV for display exceeds 100nit (normally 200 nit or more), “HDR to pseudo HDR conversionprocessing” is performed so that gradation of the luminance rangeexceeding 100 nit be maintained to some extent, instead of conversion ofthe HDR video into the SDR video of 100 nit or less. Therefore, the HDRvideo may be displayed on the SDR TV as a pseudo HDR video close to theoriginal HDR video.

When this “HDR to pseudo HDR conversion processing” technique is appliedto Blu-ray with an HDR disc storing only the HDR signal and the SDR TVconnected to the Blu-ray device as Illustrated in FIG. 26, the Blu-raydevice performs the “HDR to pseudo HDR conversion processing”, convertsthe HDR signal into the pseudo HDR signal, and sends the pseudo HDRsignal to the SDR TV. This allows the SDR TV to display a video with apseudo HDR effect by converting the received pseudo HDR signal into aluminance value. Thus, even where there is no HDR-enabled TV, when theHDR-enabled BD and HDR-enabled Blu-ray device are prepared, even the SDRTV can display a pseudo HDR video with higher display quality than thatof the SDR video.

Therefore, although it has been considered that the HDR-enabled TV isrequired for watching the HDR video, the pseudo HDR video that providesfeeling of an HDR-like effect can be watched with the existing SDR TV.Accordingly, wide use of HDR-enabled Blu-ray is expected.

26. Advantageous Effects, Etc

The HDR signal sent by broadcast, package media such as Blu-ray, andInternet delivery such as OTT is converted into the pseudo HDR signal byperforming the HDR-pseudo HDR conversion processing. This allows the HDRsignal to be displayed on the existing SDR TV as the pseudo HDR video.

27. About EOTF

Here, EOTF will be described with reference to FIG. 27A and FIG. 27B.

FIG. 27A is a diagram Illustrating an example of EOTF (Electro-OpticalTransfer Function) that supports each of HDR and SDR.

EOTF is commonly called a gamma curve, indicates correspondence betweena code value and a luminance value, and converts the code value into theluminance value. That is, EOTF is correspondence information thatindicates the correspondence between a plurality of code values and theluminance value.

FIG. 27B is a diagram illustrating an example of inverse EOTF thatsupports each of HDR and SDR.

Inverse EOTF indicates correspondence between the luminance value andthe code value, and quantizes and converts the luminance value into thecode value, inversely to EOTF. That is, inverse EOTF is correspondenceinformation that indicates the correspondence between the luminancevalue and the plurality of code values. For example, in a case ofrepresenting a luminance value of an HDR-enabled video with a code valueof 10-bit gradation, the luminance value in the luminance range of HDRof up to 10,000 nit is quantized and mapped to 1024 Integral values from0 to 1023. That is, the luminance value (luminance value of theHDR-enabled video) In the luminance range of up to 10,000 nit isconverted into the HDR signal of a 10-bit code value by quantizationbased on Inverse EOTF. In HDR-enabled EOTF (hereinafter referred to as“EOTF of HDR”) or HDR-enabled inverse EOTF (hereinafter referred to as“inverse EOTF of HDR”), it is possible to represent the luminance valuehigher than the luminance value in SDR-enabled EOTF (hereinafterreferred to as “EOTF of SDR”) or SDR-enabled inverse EOTF (hereinafterreferred to as “inverse EOTF of SDR”). For example, in FIG. 27A and FIG.27B, the maximum value of luminance (peak luminance) is 10,000 nit. Thatis, the luminance range of HDR includes the entire luminance range ofSDR, and the peak luminance of HDR is larger than the peak luminance ofSDR. The luminance range of HDR is the luminance range with the maximumvalue enlarged from 100 nit, which is the maximum value of the luminancerange of SDR, to 10,000 nit.

For example, one example of EOTF of HDR and inverse EOTF of HDR is SMPTE2084 standardized by the United States Society of Motion Picture andTelevision Engineers (SMPTE).

Note that in the following specification, the luminance range describedin FIG. 27A and FIG. 27B from 0 nit to 100 nit, which is the peakluminance, may be described as the first luminance range. Similarly, theluminance range described in FIG. 27A and FIG. 27B from 0 nit to 10,000nit, which is the peak luminance, may be described as the secondluminance range.

28. Conversion Apparatus and Display Apparatus

FIG. 28 is a block diagram Illustrating a configuration of theconversion apparatus and display apparatus according to the exemplaryembodiment. FIG. 29 is a flowchart Illustrating the conversion methodand display method to be performed by the conversion apparatus anddisplay apparatus according to the exemplary embodiment.

As illustrated in FIG. 28, conversion apparatus 100 includes HDR EOTFconverter 101, luminance converter 102, inverse luminance converter 103,and Inverse SDR EOTF converter 104. Display apparatus 200 includesdisplay setting unit 201, SDR EOTF converter 202, luminance converter203, and display unit 204.

Detailed description of each component of conversion apparatus 100 anddisplay apparatus 200 will be made in description of the conversionmethod and the display method.

29. Conversion Method and Display Method

The conversion method to be performed by conversion apparatus 100 willbe described with reference to FIG. 29. Note that the conversion methodincludes step S101 to step S104 described below.

First, HDR EOTF converter 101 of conversion apparatus 100 acquires theHDR video on which inverse EOTF conversion of HDR is performed. HDR EOTFconverter 101 of conversion apparatus 100 performs EOTF conversion ofHDR on the HDR signal of the acquired HDR video (S101). Accordingly, HDREOTF converter 101 converts the acquired HDR signal into a linear signalthat indicates the luminance value. An example of EOTF of HDR is SMPTE2084.

Next, luminance converter 102 of conversion apparatus 100 performs firstluminance conversion that converts the linear signal converted by HDREOTF converter 101 by using the display characteristic information andcontent luminance information (S102). In the first luminance conversion,the luminance value compatible with the luminance range of HDR(hereinafter referred to as “luminance value of HDR”) is converted intothe luminance value compatible with the luminance range of the display(hereinafter referred to as “display luminance value”). Details will bedescribed later.

From the aforementioned description, HDR EOTF converter 101 functions asan acquisition unit that acquires the HDR signal as a first luminancesignal indicating the code value obtained by quantization of theluminance value of a video. In addition, HDR EOTF converter 101 andluminance converter 102 function as a converter that converts the codevalue indicated by the HDR signal acquired by the acquisition unit intothe display luminance value compatible with the luminance range of thedisplay determined based on the luminance range of the display (displayapparatus 200), which is a maximum value (DPL) smaller than a maximumvalue (HPL) of the luminance range of HDR and larger than 100 nit.

More specifically, in step S101, HDR EOTF converter 101 uses theacquired HDR signal and EOTF of HDR to determine the luminance value ofHDR associated with the code value of HDR by EOTF of HDR, the code valueof HDR being a first code value indicated by the acquired HDR signal.Note that the HDR signal indicates the code value of HDR obtained byquantization of the luminance value of a video (content) by usinginverse EOTF of HDR that associates the luminance value in the luminancerange of HDR with the plurality of HDR code values.

In step S102, regarding the luminance value of HDR determined in stepS101, luminance converter 102 performs the first luminance conversionthat determines the display luminance value compatible with theluminance range of the display associated with the luminance value ofHDR in advance, and converts the luminance value of HDR compatible withthe HDR luminance range into the display luminance value compatible withthe luminance range of the display.

Before step S102, conversion apparatus 100 acquires content luminanceinformation including at least one of a maximum value of luminance (CPL:Content Peak luminance) of a video (content) and an average luminancevalue (CAL: Content Average luminance) of a video as informationregarding the HDR signal. CPL (first maximum luminance value) is, forexample, a maximum value of the luminance values of a plurality ofimages that constitute the HDR video. CAL is, for example, an averageluminance value which is an average of the luminance values of theplurality of images that constitute the HDR video.

In addition, before step S102, conversion apparatus 100 acquires thedisplay characteristic information on display apparatus 200 from displayapparatus 200. Note that the display characteristic information isinformation indicating the display characteristic of display apparatus200, such as a maximum value of luminance that display apparatus 200 candisplay (DPL), display mode (refer to later description) of displayapparatus 200, and input-output characteristic (EOTF supported by thedisplay apparatus).

In addition, conversion apparatus 100 may transmit recommended displaysetting information (refer to later description, and hereinaftersometimes referred to as “setting Information”) to display apparatus200.

Next, inverse luminance converter 103 of conversion apparatus 100performs Inverse luminance conversion according to the display mode ofdisplay apparatus 200. Accordingly, Inverse luminance converter 103performs second luminance conversion that converts the luminance valuecompatible with the luminance range of the display Into the luminancevalue compatible with the luminance range of SDR (0 to 100 [nit])(S103). Details will be described later. That is, regarding the displayluminance value obtained in step S102, inverse luminance converter 103performs the second luminance conversion that determines the luminancevalue compatible with SDR (hereinafter referred to as “SDR luminancevalue”) as a third luminance value compatible with the luminance rangeof SDR with the maximum value of 100 nit associated with the displayluminance value in advance, and converts the display luminance valuecompatible with the luminance range of the display into the SDRluminance value compatible with the luminance range of SDR.

Then, inverse SDR EOTF converter 104 of conversion apparatus 100performs inverse SDR EOTF conversion to generate the pseudo HDR video(S104). That is, inverse SDR EOTF converter 104 uses inverse EOTF(Electro-Optical Transfer Function) of SDR (Standard Dynamic Range),which is third correspondence information that associates the luminancevalue in the luminance range of HDR with a plurality of third codevalues, to quantize the determined luminance value of SDR, determinesthe third code value obtained by quantization, and converts theluminance value of SDR compatible with the luminance range of SDR intothe SDR signal as a third luminance signal Indicating the third codevalue, thereby generating the pseudo HDR signal. Here, each of the thirdcode values is a code value compatible with SDR, and hereinafterreferred to as “code value of SDR”. That is, the SDR signal is expressedby the code value of SDR obtained by quantization of the luminance valueof a video by using inverse EOTF of SDR that associates the luminancevalue in the luminance range of SDR with the plurality of code values ofSDR. Then, conversion apparatus 100 outputs the pseudo HDR signal (SDRsignal) generated in step S104 to display apparatus 200.

Conversion apparatus 100 performs the first luminance conversion and thesecond luminance conversion on the luminance value of HDR obtained byperforming inverse quantization on the HDR signal to generate theluminance value of SDR compatible with pseudo HDR. Conversion apparatus100 quantizes the luminance value of SDR by using EOTF of SDR togenerate the SDR signal compatible with pseudo HDR. Although theluminance value of SDR is a numerical value within the luminance rangeof 0 to 100 nit compatible with SDR, since conversion based on theluminance range of the display is performed, the luminance value of SDRis a numerical value different from the luminance value within theluminance range of 0 to 100 nit compatible with SDR obtained byperforming the luminance conversion using EOTF of HDR and EOTF of SDR onthe luminance value of HDR.

Next, the display method to be performed by display apparatus 200 willbe described with reference to FIG. 29. Note that the display methodincludes step S105 to step S108 described below.

First, display setting unit 201 of display apparatus 200 uses thesetting Information acquired from conversion apparatus 100 to setdisplay settings of display apparatus 200 (S105). Here, displayapparatus 200 is the SDR TV. The setting information is informationindicating display settings recommended to the display apparatus, and isinformation indicating how to perform EOTF on the pseudo HDR video andwhich display settings to use for displaying a beautiful video (that is,information for switching the display settings of display apparatus 200to optimal display settings). The setting information includes, forexample, a gamma curve characteristic of output in the displayapparatus, display modes such as a living mode (normal mode) and dynamicmode, and a numerical value of a back light (brightness). In addition, amessage may be displayed on display apparatus 200 for prompting the userto change the display settings of display apparatus 200 (hereinaftersometimes referred to as “SDR display”) by manual operation. Detailswill be described later.

Note that, before step S105, display apparatus 200 acquires the SDRsignal (pseudo HDR signal) and the setting information Indicating thedisplay settings recommended to display apparatus 200 in displaying avideo.

Display apparatus 200 only needs to acquire the SDR signal (pseudo HDRsignal) before step S106, and may acquire the SDR signal after stepS105.

Next, SDR EOTF converter 202 of display apparatus 200 performs EOTFconversion of SDR on the acquired pseudo HDR signal (S106). That is, SDREOTF converter 202 performs inverse quantization on the SDR signal(pseudo HDR signal) by using EOTF of SDR. Accordingly, SDR EOTFconverter 202 converts the code value of SDR indicated by the SDR signalinto the luminance value of SDR.

Then, luminance converter 203 of display apparatus 200 performs theluminance conversion according to the display mode that is set fordisplay apparatus 200. Accordingly, luminance converter 203 performsthird luminance conversion that converts the luminance value of SDRcompatible with the luminance range of SDR (0 to 100 [nit]) into thedisplay luminance value compatible with the luminance range of thedisplay (0 to DPL [nit]) (S107). Details will be described later.

As described above, in step S106 and step S107, display apparatus 200converts the third code value indicated by the acquired SDR signal(pseudo HDR signal) Into the display luminance value compatible with theluminance range of the display (0 to DPL [nit]) by using the settinginformation acquired in step S105.

More specifically, in the conversion from the SDR signal (pseudo HDRsignal) into the display luminance value, in step S106, by using EOTFthat associates the luminance value in the luminance range of SDR withthe plurality of third code values, display apparatus 200 determines theluminance value of SDR associated with the code value of SDR indicatedby the acquired SDR signal by EOTF of SDR.

Then, in the conversion into the display luminance value, in step S107,display apparatus 200 performs the third luminance conversion thatdetermines the display luminance value compatible with the luminancerange of the display associated in advance with the determined luminancevalue of SDR, and converts the luminance value of SDR compatible withthe luminance range of SDR into the display luminance value compatiblewith the luminance range of the display.

Finally, display unit 204 of display apparatus 200 displays the pseudoHDR video on display apparatus 200 based on the converted displayluminance value (S108).

30. First Luminance Conversion

Next, details of the first luminance conversion (HPL to DPL) of stepS102 will be described with reference to FIG. 30A. FIG. 30A is a diagramIllustrating an example of the first luminance conversion.

Luminance converter 102 of conversion apparatus 100 performs the firstluminance conversion of converting the linear signal (luminance value ofHDR) obtained in step S101 by using the display characteristicinformation and the content luminance information on the HDR video. Thefirst luminance conversion converts the luminance value of HDR (inputluminance value) into the display luminance value (output luminancevalue) that does not exceed the display peak luminance (DPL). DPL isdetermined using the maximum luminance of the SDR display and thedisplay mode which are the display characteristic information. Thedisplay mode is, for example, mode information including a theater modeof relatively dark display on the SDR display and a dynamic mode ofrelatively bright display. When the display mode is, for example, a modein which the maximum luminance of the SDR display is 1,500 nit, and thedisplay mode is a mode in which brightness is set to 50% of the maximumluminance. DPL will be 750 nit. Here, DPL (second maximum luminancevalue) is a maximum value of luminance the SDR display can display inthe display mode of current setting. That is, in the first luminanceconversion, DPL as the second maximum luminance value is determined byusing the display characteristic information which is informationindicating the display characteristic of the SDR display.

In addition, in the first luminance conversion, CAL and CPL out of thecontent luminance information are used. The luminance value equal to orless than vicinity of CAL is identical between before and after theconversion, and only the luminance value equal to or greater thanvicinity of CPL is changed. That is, as Illustrated in FIG. 30A, in thefirst luminance conversion, when the luminance value of HDR is equal toor less than CAL, the luminance value of HDR is not converted, and theluminance value of HDR is determined as the display luminance value.When the luminance value of HDR is equal to or greater than CPL, DPL asthe second maximum luminance value is determined as the displayluminance value.

In addition, in the first luminance conversion, out of the luminanceinformation, the peak luminance of the HDR video (CPL) is used. When theluminance value of HDR is CPL, DPL is determined as the displayluminance value.

Note that, in the first luminance conversion, as illustrated in FIG.30B, conversion may be performed so that the linear signal (luminancevalue of HDR) obtained in step S101 may be clipped to a value that doesnot exceed DPL. Such luminance conversion can simplify processingperformed by conversion apparatus 100, and can achieve size reduction,low power consumption, and high-speed processing of the apparatuses.Note that FIG. 30B is a diagram Illustrating another example of thefirst luminance conversion.

[31-1. Second Luminance Conversion]

Next, details of the second luminance conversion of step S103 (DPL to100 [nit]) will be described with reference to FIG. 31. FIG. 31 is adiagram illustrating the second luminance conversion.

Inverse luminance converter 103 of conversion apparatus 100 appliesinverse luminance conversion according to the display mode to thedisplay luminance value in the luminance range of the display convertedin the first luminance conversion of step S102 (0 to DPL [nit]). Theinverse luminance conversion is processing for acquiring the displayluminance value in the luminance range of the display after processingof step S102 (0 to DPL [nit]) when the luminance conversion processing(step S107) according to the display mode is performed by the SDRdisplay. That is, the second luminance conversion is the inverseluminance conversion of the third luminance conversion.

By the aforementioned processing, the second luminance conversionconverts the display luminance value in the luminance range of thedisplay (input luminance value) into the luminance value of SDR in theluminance range of SDR (output luminance value).

In the second luminance conversion, a conversion equation is switchedaccording to the display mode of the SDR display. For example, when thedisplay mode of the SDR display is the normal mode, the luminanceconversion is performed to a direct proportion value in directproportion to the display luminance value. In the second luminanceconversion, when the display mode of the SDR display is the dynamic modein which a high-luminance pixel becomes brighter and a low-luminancepixel becomes darker than pixels in the normal mode, the luminanceconversion is performed by using an inverse function thereof so that theluminance value of SDR of the low-luminance pixel is converted into avalue higher than the direct proportion value in direct proportion tothe display luminance value, and that the luminance value of SDR of thehigh-luminance pixel is converted into a value lower than the directproportion value in direct proportion to the display luminance value.That is, in the second luminance conversion, regarding the displayluminance value determined in step S102, by using luminance-relatedinformation according to the display characteristic information which isinformation indicating the display characteristic of the SDR display,the luminance value associated with the display luminance value isdetermined as the luminance value of SDR, and the luminance conversionprocessing is switched according to the display characteristicinformation. Here, the luminance-related information according to thedisplay characteristic information refers, for example as illustrated inFIG. 31, to information that associates the display luminance value(input luminance value) with the luminance value of SDR (outputluminance value) defined for each display parameter of the SDR display(display mode).

[31-2. Third Luminance Conversion]

Next, details of the third luminance conversion of step S107 (100 to DPL[nit]) will be described with reference to FIG. 32. FIG. 32 is a diagramIllustrating the third luminance conversion.

Luminance converter 203 of display apparatus 200 converts the luminancevalue of SDR in the luminance range of SDR (0 to 100 [nit]) into (0 toDPL [nit]) according to the display mode that is set in step S105. Thisprocessing is performed so as to become an inverse function of theinverse luminance conversion for each mode of S1103.

In the third luminance conversion, the conversion equation is switchedaccording to the display mode of the SDR display. For example, when thedisplay mode of the SDR display is the normal mode (that is, when theset display parameter is a parameter compatible with the normal mode),the luminance conversion of the display luminance value is performed tothe direct proportion value in direct proportion to the luminance valueof SDR. In the third luminance conversion, when the display mode of theSDR display is the dynamic mode in which a high-luminance pixel becomesbrighter and a low-luminance pixel becomes darker than pixels in thenormal mode, the luminance conversion is performed so that the displayluminance value of the low-luminance pixel is converted into a valuelower than the direct proportion value in direct proportion to theluminance value of SDR, and that the display luminance value of thehigh-luminance pixel is converted into a value higher than the directproportion value in direct proportion to the luminance value of SDR.That is, in the third luminance conversion, regarding the luminancevalue of SDR determined in step S106, by using luminance-relatedInformation according to the display parameter indicating the displaysettings of the SDR display, the luminance value associated in advancewith the luminance value of SDR is determined as the display luminancevalue, and the luminance conversion processing is switched according tothe display parameter. Here, the luminance-related information accordingto the display parameter refers, for example as illustrated in FIG. 32,to information that associates the luminance value of SDR (inputluminance value) with the display luminance value (output luminancevalue) defined for each display parameter of the SDR display (displaymode).

32. Display Settings

Next, details of the display settings of step 6105 will be describedwith reference to FIG. 33. FIG. 33 is a flowchart illustrating detailedprocessing of the display settings.

In step 6105, display setting unit 201 of the SDR display performs stepS201 to step S208 described below.

First, display setting unit 201 uses the setting information todetermine whether EOTF that is set for the SDR display (EOTF for SDRdisplay) is consistent with EOTF assumed at a time of generation of thepseudo HDR video (SDR signal) (S201).

When display setting unit 201 determines that EOTF that is set for theSDR display differs from EOTF indicated by the setting information (EOTFconsistent with the pseudo HDR video) (Yes in S201), display settingunit 201 determines whether EOTF for the SDR display is switchable on asystem side (S202).

When display setting unit 201 determines that EOTF for the SDR displayis switchable, display setting unit 201 uses the setting information toswitch EOTF for the SDR display to appropriate EOTF (S203).

From step 6201 to step 6203, in setting of the display settings (S105),display setting unit 201 sets EOTF that is set for the SDR display asrecommended EOTF according to the acquired setting information. Thisallows determination of the luminance value of SDR by using therecommended EOTF in step S106 to be performed after step S105.

When display setting unit 201 determines that EOTF for the SDR displayis not switchable on the system side (No in S202), display setting unit201 displays a message on a screen prompting the user to change EOTF bymanual operation (S204). For example, display setting unit 201 displaysa message on the screen saying “Set display gamma to 2.4”. That is, whendisplay setting unit 201 cannot switch EOTF that is set for the SDRdisplay in setting of the display settings (S105), display setting unit201 displays the message on the SDR display for prompting the user toswitch EOTF that is set for the SDR display (EOTF for the SDR display)to the recommended EOTF.

Next, although the SDR display displays the pseudo HDR video (SDRsignal), before the display, display setting unit 201 uses the settinginformation to determine whether the display parameter of the SDRdisplay matches the setting information (S205).

When display setting unit 201 determines that the display parameter thatis set for the SDR display differs from the setting information (Yes inS205), display setting unit 201 determines whether the display parameterof the SDR display is switchable (S206).

When display setting unit 201 determines that the display parameter ofthe SDR display is switchable (Yes in S206), display setting unit 201switches the display parameter of the SDR display in accordance with thesetting information (S207).

From step S204 to step S207, in setting of the display settings (S105),display setting unit 201 sets the display parameter that is set for theSDR display as a recommended display parameter according to the acquiredsetting information.

When display setting unit 201 determines that the display parameter ofthe SDR display is not switchable on the system side (No in S206),display setting unit 201 displays a message on the screen prompting theuser to change the display parameter that is set for the SDR display bymanual operation (S208). For example, display setting unit 201 displaysa message on the screen saying “Set display mode to dynamic mode, andincrease back light to maximum lever”. That is, in setting (S105), whenthe display parameter that is set for the SDR display cannot beswitched, display setting unit 201 displays the message on the SDRdisplay for prompting the user to switch the display parameter that isset for the SDR display to the recommended display parameter.

33. Variation 1

As described above, the exemplary embodiment has been described by wayof example of the technique to be disclosed in this application.However, the technique in the present disclosure is not limited to thisexample, and is also applicable to the first exemplary embodiment towhich change, replacement, addition, omission, etc. are made asappropriate. It is also possible to make a new exemplary embodiment bycombining components described in the aforementioned exemplaryembodiment.

Therefore, other exemplary embodiment will be illustrated below.

The HDR video is, for example, a video within a Blu-ray disc, DVD, videodelivery site on the Internet, broadcast, and HDD.

Conversion apparatus 100 (HDR to pseudo HDR conversion processor) mayexist within a disc player, disc recorder, set-top box, TV, personalcomputer, and smart phone. Conversion apparatus 100 may exist within aserver apparatus on the Internet.

Display apparatus 200 (SDR display unit) is, for example, a TV, personalcomputer, and smart phone.

The display characteristic information to be acquired by conversionapparatus 100 may be acquired from display apparatus 200 through an HDMIcable or LAN cable by using HDMI or other communication protocols. Asthe display characteristic information to be acquired by conversionapparatus 100, display characteristic information included in modelinformation on display apparatus 200, etc. may be acquired via theInternet. The user may perform manual operation to set the displaycharacteristic information in conversion apparatus 100. Acquisition ofthe display characteristic information by conversion apparatus 100 maybe performed immediately before pseudo HDR video generation (steps S101to S104), and may be performed with timing of initial setting of adevice or display connection. For example, acquisition of the displaycharacteristic information may be performed immediately beforeconversion into the display luminance value, and may be performed withtiming with which conversion apparatus 100 is connected to displayapparatus 200 with an HDMI cable for the first time.

One set of information items including CPL and CAL of the HDR video mayexist per one piece of content, and may exist for each scene. That is,in the conversion method may be acquired luminance information (CPL,CAL) compatible with each of a plurality of scenes in a video, theluminance information including, for each of the scenes, at least one ofa first maximum luminance value which is a maximum value out of theluminance values of a plurality of images that constitute the scene, andan average luminance value which is an average of the luminance valuesof the plurality of images that constitute the scene. In the firstluminance conversion, the display luminance value may be determined inaccordance with luminance information corresponding to each of theplurality of scenes.

CPL and CAL may be provided in a medium (such as a Blu-ray disc and DVD)identical to a medium of the HDR video, and may be acquired from a placedifferent from the HDR video, such as conversion apparatus 100 acquiresCPL and CAL from the Internet. That is, the luminance informationincluding at least one of CPL and CAL may be acquired as metadatainformation on the video, and may be acquired via a network.

In the first luminance conversion of conversion apparatus 100 (HPL toDPL), CPL, CAL, and the display peak luminance (DPL) may not be used,and fixed values may be used. The fixed values may be changeable fromoutside. CPL, CAL, and DPL may be switched among several types, forexample, DPL may be only three types including, 200 nit, 400 nit, and800 nit, and a value closest to the display characteristic informationmay be used.

EOTF of HDR may not be SMPTE 2084, and EOTF of HDR of another type maybe used. The maximum luminance of the HDR video (HPL) may not be 10,000nit, and may be, for example, 4,000 nit or 1,000 nit.

A bit width of the code value may be, for example, 16, 14, 12, 10, or 8bits.

Although inverse EOTF conversion of SDR is determined from the displaycharacteristic information, a fixed (changeable from outside) conversionfunction may be used. Inverse EOTF conversion of SDR may use, forexample, a function prescribed by Rec. ITU-R BT.1886. Types of inverseEOTF conversion of SDR may be limited to several types, and a typeclosest to an input-output characteristic of display apparatus 200 maybe selected and used.

A fixed mode may be used as the display mode, and the display mode maynot be included in the display characteristic information.

Conversion apparatus 100 may not transmit the setting information,display apparatus 200 may use fixed display settings, and may not changethe display settings. In this case, display setting unit 201 isunnecessary. The setting information may be flag information indicatingwhether a video is the pseudo HDR video, and for example, when a videois the pseudo HDR video, settings may be changed to brightest display.That is, in setting of the display settings (S105), when the acquiredsetting information indicates a signal indicating the pseudo HDR videothat is converted using DPL, brightness settings of display apparatus200 may be switched to settings of brightest display.

34. Variation 2

The first luminance conversion (HPL to DPL) of conversion apparatus 100is performed by the next formula, for example.

Here, L denotes a luminance value normalized to 0 to 1, and S1, S2, a,b, and M are values to be set based on CAL, CPL, and DPL. In is anatural logarithm. V is a converted luminance value normalized to 0to 1. As in the example of FIG. 30A, when CAL is 300 nit, CPL is 2,000nit, DPL is 750 nit, conversion is not performed until CAL+50 nit, andconversion is performed for 350 nit or more, respective values are asfollows, for example.

S1=350/10,000

S2=2,000/10,000

M=750/10,000

a=0.023

b=S1−a ln(S1)=0.112105

That is, in the first luminance conversion, when the luminance value ofSDR is between the average luminance value (CAL) and the first maximumluminance value (CPL), the display luminance value corresponding to theluminance value of HDR is determined using a natural logarithm.

35. Advantageous Effects, Etc

By converting the HDR video by using information including the contentpeak luminance and content average luminance of the HDR video, theconversion equation may be changed according to content, and it ispossible to perform conversion so that gradation of HDR may bemaintained as much as possible. It is also possible to inhibit anadverse effect such as too dark and too bright. Specifically, by mappingthe content peak luminance of the HDR video on the display peakluminance, gradation is maintained as much as possible. In addition,overall brightness is kept from changing by not changing a pixel valueequal to or less than vicinity of the average luminance.

By using the peak luminance value and the display mode of the SDRdisplay to convert the HDR video, the conversion equation may be changedin accordance with display environments of the SDR display. Inaccordance with performance of the SDR display, a video with feeling ofHDR (pseudo HDR video) may be displayed with gradation and brightnesssimilar to gradation and brightness of an original HDR video.Specifically, by determining the display peak luminance in accordancewith the maximum luminance and display mode of the SDR display, and byconverting the HDR video so as not to exceed the peak luminance value,the HDR video is displayed with little reduction in gradation of the HDRvideo until brightness that is displayable by the SDR display. Fornon-displayable brightness levels, the luminance value is decreased to adisplayable brightness level.

This makes it possible to reduce non-displayable brightness information,and to display video in a form close to the original HDR video withoutreducing gradation of displayable brightness. For example, for a displaywith a peak luminance of 1,000 nit, overall brightness is maintained byconversion into the pseudo HDR video with a peak luminance reduced to1,000 nit, and the luminance value changes depending on the display modeof the display. Therefore, the conversion equation of luminance ischanged according to the display mode of the display. If luminancegreater than the peak luminance of the display is allowed in the pseudoHDR video, such great luminance may be replaced with the peak luminanceon the display side for display. In this case, the display becomesdarker than the original HDR video on the whole. In contrast, when theconversion is performed with the luminance smaller than the peakluminance of the display as the maximum luminance, such small luminanceis replaced with the peak luminance on the display side, and the displaybecomes brighter than the original HDR video on the whole. Moreover,this does not make the most of performance regarding gradation of thedisplay because the luminance is smaller than the peak luminance on thedisplay side.

On the display side, this makes it possible to better display the pseudoHDR video by switching the display settings by using the settinginformation. For example, when brightness is set to dark, high-luminancedisplay is not possible, and thus feeling of HDR is impaired. In thiscase, by changing the display settings or by displaying a messageprompting to change the display settings, maximum performance of thedisplay is brought out, and a high-gradation video may be displayed.

(Overall Summary)

Although the playback method and the playback apparatus according to oneor more aspects of the present disclosure have been described above onthe basis of the exemplary embodiment, the present disclosure is notlimited to this exemplary embodiment. The exemplary embodiment to whichvarious modifications conceivable by a person skilled in the art aremade, and aspects that are made by combining elements of differentexemplary embodiment may also be within the scope of the one or moreaspects of the present disclosure as long as such aspects do not departfrom the gist of the present disclosure.

For example, in the aforementioned exemplary embodiment, each componentmay be made of dedicated hardware such as a circuit, or may beimplemented through execution of a software program suitable for eachcomponent. Each component may be implemented by a program executionunit, such as a CPU or a processor, reading and executing the softwareprogram recorded in a recording medium such as a hard disk or asemiconductor memory.

The present disclosure is applicable to content data generationapparatuses, video stream transmission apparatuses such as a Blu-raydevice, or video display apparatuses such as a TV.

What is claimed is:
 1. A display apparatus comprising a data outputapparatus, the data output apparatus comprising: a decoder that decodesa video stream to generate a first video signal with a first luminancerange; an acquirer that acquires metadata regarding a luminance range ofthe first video signal; an interpreter that interprets the metadata toacquire characteristic data indicating the luminance range of the firstvideo signal and conversion auxiliary data for converting the luminancerange of the first video signal; an output unit that outputs controlinformation including the characteristic data; and a converter thatconverts the luminance range of the first video signal based on theconversion auxiliary data to generate a second video signal with asecond luminance range narrower than the first luminance range, whereinthe output unit outputs the first video signal to the display apparatuswhen the display apparatus supports video output with the luminancerange of the first video signal, and the output unit outputs the secondvideo signal to the display apparatus when the display apparatus doesnot support the video output with the luminance range of the first videosignal.
 2. The display apparatus according to claim 1, wherein theoutput unit outputs the second video signal and information to thedisplay apparatus, the information being to cause the display apparatusto display that the second video signal obtained through conversion fromthe first luminance range into the second luminance range is displayedto the display apparatus.
 3. The display apparatus according to claim 1,wherein the metadata includes type information indicating whetherinterpretation of the metadata is necessary or not, the interpreter usesthe type information to determine whether the interpretation of themetadata is necessary or not, and further determines whether theinterpreter can interpret the metadata when the interpretation of themetadata is not necessary, and when the interpreter can interpret themetadata, the interpreter interprets the metadata to acquire thecharacteristic data and the conversion auxiliary data.
 4. The displayapparatus according to claim 1, wherein the metadata is a dynamicmetadata which is variable for each scene in the video stream; and theoutput unit outputs the control information while synchronizing with thefirst video signal or the second video signal of which the dynamicmetadata becomes effective.
 5. A data output method performed by a dataoutput apparatus with which a display apparatus is provided, the methodcomprising: decoding a video stream to generate a first video signalwith a first luminance range; acquiring metadata regarding a luminancerange of the first video signal; interpreting the metadata to acquirecharacteristic data indicating the luminance range of the first videosignal and conversion auxiliary data for converting the luminance rangeof the first video signal; outputting control information including thecharacteristic data; and converting the luminance range of the firstvideo signal based on the conversion auxiliary data to generate a secondvideo signal with a second luminance range narrower than the firstluminance range, wherein the outputting step outputs the first videosignal to the display apparatus when the display apparatus supportsvideo output with the luminance range of the first video signal, and theoutputting step outputs the second video signal to the display apparatuswhen the display apparatus does not support the video output with theluminance range of the first video signal.